[CF-metadata] standard names

From: Brian Eaton <eaton>
Date: Sat, 15 Nov 2003 14:10:38 -0700

Hi Pieter and Jonathan,

> > If you are interested in elevation and we need to define
> > which geoid is used
> > we will have to do some more work. This is an area which we haven't
> > considered because it's not relevant for models.
>
> Would height_datum and depth_datum be suitable?

The issue of specifying the geoid has also come up recently in the context
of defining map projections. For defining geodetic models the FGDC doc
provides horizontal_datum_name and ellipsoid_name to identify published
references, e.g., "North American Datum of 1983", and "Geodetic Reference
System 80". It seems that we should allow these attributes to be attached
either to variables containing data which requires knowlege of the geoid
for correct interpretation, or to variables that define map projections.

If we take the path of including information that identifies the geoid in
standard names then the problem arises of providing a new standard name for
each geoid or horizontal datum reference of interest. I seems better to
keep this information out of the standard name and provide separate
attributes for it since it's really part of defining the spatial coordinate
system.

> > The velocity components relative to the local x- and
> > y-directions on the grid
> > should be called grid_eastward_sea_water_velocity and
> > grid_northward_sea_water_velocity (as for winds). These
> > standard names are not in the table but I propose we should add them.
>
> East and north even if the grid direction is somewhere in between and
> location dependent? (picture in attachment)

I agree that using east and north in contexts where they don't apply is
confusing. We have, for example, names like projection_x_coordinate, and
projection_y_coordinate to identify projection coordinates. Perhaps we
could use names like x_sea_water_velocity and y_sea_water_velocity with
descriptions to indicate that the x velocity component is positive in the
direction of increasing x-coordinate.

Brian
Received on Sat Nov 15 2003 - 14:10:38 GMT